Door-alarm



June 10, 1958 A. J EZL DOOR-ALARM Filed July 25. 1956 PM QM 2 Sheets-Sheet 1 ATTORNEYS June 10, 1958 A. JEZL 2,838,747

DOOR-ALARM Filed July 25, 1956 2 Sheets-Sheet 2 INVENTOR.

fin to 71 J22 z Z ATTORNEYS 2,838,747 Patented June 10, 1958 United States Patent Ofiice DOOR-ALARM Anton Jezl, Chicago, Ill.

Application July 25, 1956, Serial No. 600,007

2 Claims. (Cl. 340-274) characters denote corresponding parts the improved burglar alarm of this invention includes a base plate 10, a cover 11, a bell clapper 12, a rotary switch 13 positioned in the cover or case and adapted to be opened and closed by a button 14, batteries 15 and 16 positioned in the case for supplying current to the bell clapper coils 17 and 18 and contacts 19 and 20 for opening a circuit to the device with the door in the closed position.

The base plate 10 is secured to the inner surface of a door 21 by screws, or othersuitable fastening means and the edges of the side walls 22 and 23 and end Walls 24 and 25 of the case are secured to the base plate with screws 26. The base plate 10 is positioned over an opening 27 in the door 21 and, as shown particularly in Fig. 3, a cylinder lock 28, positioned in the opening 27 and having a face plate 29, and which is provided with terminals the bell clapper when a door is opened without the con- 5 ventional key.

The purpose of this invention is to provide a burglar alarm adapted to be mounted on the inner surface of a door wherein parts operate to sound an alarm when the door is opened by an intruder.

Various types of alarm devices have been used in combination with doors, windows, and the like, however, it is difficult to provide a device that is self contained and that may be installed by the average individual. With this thought in mind this invention contemplates a box or casing adapted to be secured on the inner surface of a door with wood screws in which the device is set with a thumb screw so that upon opening the door without first turning the lock bolt with a key an alarm is sounded.

The object of this invention is, therefore, to provide a safety alarm that is adapted to be used on the inner surface of a doorin which the parts are adapted to be set by turning a knob so that upon opening the door a circuit is completed to sound an alarm.

Another object of the invention is to provide a safety alarm for a door in which the device is adapted to be tested periodically.

A further object of the invention is to provide an alarm adapted to be used on the inner surface of a door in which the device is of a simple and economical construction.

With these and other objects and advantages in view the invention embodies a comparatively small, substantially rectangular-shaped casing with contact bars positioned in the casing and with means in the casing for sounding an alarm when contacts of the bars are closed by an intruder opening the door.

Other features and advantages of the invention will appear from the following description take in connection with the drawings, wherein:

Figure 1 is a front elevational view with the cover of the casing omitted and showing the parts of the alarm device mounted on the base thereof.

Figure 2 is a side elevational view of the alarm device with part of the casing broken away and also with partsshown in section.

Figure 3 is a vertical section through the device with the alarm mounted on a door and with part of the door broken away showing a lock cylinder therein.

Figure 4 is a sectional plan through the safety lock showing the relative positions of the parts and also showing the device on a door with the conventional lock cylinder extended through the door.

Figure 5 is a view showing a typical wiring diagram of the improved safety door lock.

Referring now to the drawings wherein like reference 30 and 31, is connected by a wire 32 to a terminal 33 of a contact bar 34 of a switch'having contacts 35 and 36;

the wire 32 being connected to the terminal 30 of the cylinder block 28 and the terminal 31 thereof being connected by a wire 37 to a terminal 38 in a bracket 39, the terminal 38 being positioned to be engaged by a terminal 40 0f the battery 16. A key actuated lock 28 is connected by the wires 32 and 37 to operative parts of the alarm device whereby with the lock actuated by a'key the alarm is inoperative whereas with the door forced open without a key in the lock the alarm is sounded.

The contact or bus bar 34 is secured in a block 41 of insulating material and a similar bar 42 positioned parall'el to the bar 34 and carrying the contact 36 is also mounted in the block.

The terminal or post 33 on which a flat section 43 of the wire 37 is secured by a nut 44 is also provided with a flat section 45 of a wire 46 which extends to the button actuated switch 13 and the opposite terminal of the switch is connected by a wire 47 to the terminal 33 of the bar 34. The bus bar 42 is urged away from the bus bar 34 wherein the contacts 35 and 36 are disengaged, by a pin 48 extended upwardly from a bar 49 extended from the arm 20 and as the door 21 moves outwardly away from the jamb 50 a spring 51 connected at the point 52 to the bar 49 and to a lug 53 on the base 10, slides the bar-.49 outwardly whereby the contact 36 engages the contact 35, completing a circuit through the coils 17 and 18 of the bell clapper. In the closing movement the arm 20 engages the spring clip 19 whereby the arm 20 is moved against the edge 54 of the door and with continued closing movement of the door the arm 20 engages the areuate section 55 of the clip 19, sliding the bar 49 inwardly and opening the contacts 35 and 36.

The bar 49 is slidably mounted on the base 10 with screws 56 that'extend through slotted openings 57 in the bar and as the arm 20 engages the arcuate portion 55 of the clip 19 the bar 49 slides inwardly with the slots 57 passing over the screws 56.

The bell clapper arm 12 is mounted with a conventional spring 58 on a post 59 and the movement of the clapper is adjusted by a screw 60 on a spring arm 61.

The bell clapper 12 is positioned to engage a post 62 mounted by a ring 63 on the base plate 10 and the parts are retained in position with a spring arm 64 extended from the upper edge of the base plate.

The batteries 15 and 16 are retained in position upon the base with spring clips 65 and the outer wall 66 is provided with spaced slots or louvers 67 to provide ventilation through the casing.

' With the parts assembled asillustrated and described it will be noted, particularly in Fig. 5 that with the door closed whereby the contacts 35 and 36 are separated, with the button actuated switch 13 closed by the knob 14 and with the terminals 30 and 31 of the lock cylinder 28 closed a circuit to ring the bell is not completed and,

3 as shown in Figs. 1 and 4, closing the door opens the contacts 35 and 36 so that with the door closed the alarm circuit is not complete and the clapper of the bell is inoperative.

Upon opening the door with the key wherein turning the key actuates the contacts 30 and 31 to an open po sition so that if the door is opened with the key, in the conventional manner, the device will not operate and consequently will not sound an alarm; however if an attempt is made to open the door without the key wherein the contacts 30 and 31 remain in engagement the spring 51 snaps the arm 21 outwardly as soon as the opening movement starts wherein the end of the arm 20 passes beyond the outer end of the clip 19 and with the spring. 51 pulling the arm 20 away from the end surface 5% of the door the contact 36 is permitted to engage the contact 35 so that a complete circuit is provided and the bell clapper will operate to sound an alarm. The continuous beating of the bell clapper upon the end of the post or rod 62 provides a relatively loud tapping noise. The noise of the clapper may be adjusted by the screw 60 in the end of the spring arm 51 of the bell clapper.

It will be understood that modifications, within the scope of the appended claims, may be made in the design and arrangement of the parts without departing from the spirit of the invention.

What is claimed is:

1..In an alarm device for a door, the combination which comprises a base plate adapted to be mounted on a door, a bell clapper assembly mounted on the base plate, a post mounted on the base plate and positioned to be engaged by the bell clapper, a key actuated cylindrical lock and switch mounted in the door, a casing positioned over the parts and mounted on the base plate, a manually actuated switch mounted in the casing and having a knob extended from the casing, a

4 pair of contacts suspended by bus bars in the casing, a bar having an arm on the extended end slidably mounted on the base plate and positioned in the casing, means on the bar for opening the contacts of the bus bars upon closing movement of the door, means mounted on the door jamb for engaging the arm of the plate slidably mounted on the base upon closing movement of the door, a circuit connecting the switches and bell clapper assembly, and means for supplying electric current to said circuit.

2. In alarm device for a door, the combination which comprises a base plate adapted to be mounted on a door, a bell clapper assembly mounted on the base plate, a post mounted on the base plate and positioned to be engaged by the bell clapper, a key actuated cylindrical lock and switch mounted in the door, a casing positioned over the parts and mounted on the base plate, a manually actuated switch mounted in the casing and having a knob extended from the casing, a pair of contacts suspended by bus bars in the casing, a bar having an arm on the extended end slidably mounted on the base plate and positioned in the casing, means on the bar for opening the contacts of the bus bars upon closing movement of the door, means mounted on the door jamb for engaging the arm of the plate slidably mounted on the base upon closing movement of the door, a circuit connecting the switches and bell clapper assembly, and batteries positioned in the casing and connected in the circuit for supplying current to said circuit.

References Cited in the file of this patent UNITED STATES PATENTS 

